1. Field of the Invention
The invention relates to a chalk line device containing a spool of line which passes through a chamber filled with powdered chalk, the device being capable of being used as a chalk line assembly.
2. Description of the Prior Art
Chalk line devices are used for striking lines by carpenters, bricklayers, and various other artisans for the purpose of marking straight lines upon rough or irregular surfaces.
The field of chalk line devices is well developed, and many types and forms are available on the market. For example, U.S. Pat. No. 1,208,068 describes a device having a chalk line reel for holding a chalk line, the device comprising a frame for supporting the chalk line reel, the frame being constructed to provide a receptacle for containing pulverized chalk, and the line passing through the receptacle so that the line may be covered with the chalk as the line is drawn out. A spring is included in the frame and is coupled to a shaft supporting the reel so that after a portion of the chalk line is drawn out, the spring is tensioned so that upon release of the chalk line, the withdrawn portion of the chalk line is rewound on the reel. One disadvantage of this type of chalking device is that no provision is made for immobilizing the wound spring after a predetermined length of the chalk line is withdrawn, otherwise, as soon the chalk line is released, it is drawn immediately into the frame by the tensioned spring.
Another form of a chalk line device is described is U.S. Pat. No. 4,192,078, wherein the device is provided with a locking mechanism for restraining a chalk line against the tension of the spring when a portion of the chalk line is withdrawn from the device.
The main disadvantage of the chalk line devices described in the foregoing two references, as well as other types of retractable-type chalk line devices, is of the limitation imposed by the physical constants of the springs used for retracting the chalk line into the interior of the devices. In other words, only a predetermined length of chalk line can be withdrawn from a device. After the spring is wound to its utmost, no further withdrawal of chalk line can occur. Therefore, the length of the line is limited by the spring.